Electric switch



2 Sheets-Sheet 1 G. A. BURNHAM snscrnrc swr'rcu Filed m 2s, 1920' Patented Oct. 27, 1925.

UNITED STATES PATENT OFFICE.

GEORGE A. BURNHAM, OF SAUGUS, MASSACHUSETTS, ASSIG-NOR, BY MESNE ASSIGN- MENTS, T0 CONDIT ELECTRICAL MANUFACTURING COMPANY, A CORPORATION OF MASSACHUSETTS.

ELECTRIC SWITCH.

Application filed January 29, 1920. Serial No. 354,920.

To all whom it may concern: I

Be it known that I, GEORGE A. BURNHAM, a. citizen of the United States, residingat Saugus, in the county of Essex and State of Massachusetts, have invented an Improvement in Electric Switches, of which the fol lowing is a specification.

My present invention relates to oil immersed electric switches of relatively high current carrying capacity.

In another application, Serial No. 309,853,

filed July 10, 1919, I have SliOWIl 1 switch I wall trengthening means,

of such type having means by which to reduce the gaseous pressure within the switch and to absorb energy developed upon circuit interruption, comprising a resiliently supported oil receptacle adapted to be moved downward upon the development ofan ab normal gas pressure within the switch As an'object of my present invention, I

provide means whereby the oil contained in the switch is adapted to move or yield upon the development of an abnormal gaseous pressure within the switch, whereby to increase the expansion space of the switch and to absorb energy upon circuit interruption.

To accomplish this result I provide the switch with a double oil receptacle, one receptacle within the other, and in free oil communication at their lower ends. The inner receptacle is adapted'to contain the switch members and the outer receptacle has a closed top whereby to retain air r other gases which serve as an elastic cushion against which the oil is forced upon the development of gaseous pressure during circuit interruption and by which energy is absorbed. I may also removably depend the double oil receptacle yieldingly from the plan view along line of Fig. 1.

Fig. at is a vertical section of a modified form of double oil receptacle.

Fig. 5 is a side elevation, partly broken away, of the oil receptacle of Fig. 4-.

Fig. 6 is a detail of a modified form of As here shown, the oil switch with which my invention is associated includes the fixed switch-supporting frame having the arm 11 by which the switch is secured to a support and bearing the stationary switch-members 12, the movable switch member 13 and switch-operating mechanism 14. Said switch frame is formed with the peripheral depending flange or apron 15 adapted to sui' round and be closely spaced from the top of the oil receptacle thereby to provide a vent space 15", for the switch.

The oil receptacle of the switch comprises the inner receptacle 16 forn'iing an inner compartment and the outer receptacle 17 containing and peripherally spaced from the inner receptacie and forming an outer compartment. In Fig. 1, the inner oil receptacle is shown as having an open bottom terminating above the bottom of the outer oil receptacle whereby to provide a passage of ample dimensions for the relatively unrestricted flow of oil between the two recep tacles. In Fig. 4 the inner oil receptacle is illustrated as closed by the bottom 18, and a plurality of perforations or apertures 18 are formed in the side walls of the inner receptacle, close to the bottom thereof, whereby to provide for free oil conu'nunication between the receptacles.

The side walls of the inner receptacle extend above the top of the outer receptacle and are received within the apron 15 of the switch frame which comprises a cover for the oil receptacle. The top of the outer oil receptacle is closed by reflexing the top of its side walls into contact with the side walls of the inner receptacle and sealing the connection as by welding, in such a manner as to form a practically air tight joint. By this construction a closed space or chamber 19 is formed between the two receptacles and at the top of the outer receptacle in which air or other gases are. entrapped, when the receptacles are filled with oil to the designed level; and the oil receptacle thus formed has the reduced top-portion and the enlarged body-portion extending beyond and depending below the flange and the oil receptacle is removably secured'yieldingly to the switchframe, and the tension of the sp'rin'gsana'y 'be adjusted, whereby to yield under predetermined gaseous pressure conditions "within the switch. The means whereby the double cil'r'eceptacle is sup-' ported yieldingly from the switch frame may 'be omitted if desired without detracting from the value of my invention 'butI find it ottvalue when associated therewith.

Said springs 26 are adapted to retain the oil receptacle in substantial'contact with the underside of the switch frame and the irregularities of'the "frame and the top of the re ceptacle'are sutticient to provide a proper gas vent over the top o'f-the receptacle into the vent space between the apron '15 and down over the side walls of the receptacle 'However stop-mem.

into the atmosphere. hers-28 fixed-to said supporting rods 23 may be arranged to engage said lugs thereby to govern the height of thergas vent over the top of the oil receptacle.

Reinforcing means are arranged between the'side walls of the two receptacles where- 'byto support the side walls of the inner-re ceptacle against lateral pressure, and

In Figs. 1, 2 and 3 the reinforcing means comprises a plurality of cups 29 fixed by welding or otherwise at spaced intervalsto the inner side of the Walls of the outer receptacle and extended in proximity to the inner receptacle. In Figs. 41, 5 and 6 the supporting means comprises the channel members 30 secured by-the side walls thereof to the innerface of the outer receptacle;

and the walls of the channel-members may be provided with slots or openings 31 therethrough whereby to admit of the flow of oil through the space between the two receptacles. Said channel members are continuous, and provide considerable resistance to lateral distortion of the side walls.

The oil receptacle is adapted to be filled with oil to some suitable level aa,-'Fig. 1, oyer the stationary and movable switch members, and the oil will enter the space between the oil receptacles and be at'the samelevel' on'b'oth receptacles;and the top of the chamber 19 willcontain'air' or other gases. A pet cock 32 arranged in the top of the outer oil receptacle is in communication with said space 19 whereby to provide a vent for said chamber when the receptacle is-fillejd with oilia'nd is thenadaptedto beiclosed so that the compression space :is substantially air tight. The oil level in the receptacle is adapted to be'such thatasubstantiahgas-expansi'on space 33 is provided betweenythe top of the oil in the inner oil-receptacle and the switch frame.

Upon the-interruption of a circuitcarrying current, the heat of the resulting am will cause thezgeneration otgas within the inner oil receptacle and the pressure therein will sharply rise. The increase of ,'pressure causes an unbalancing of,pressure on the oil in;theinne r andouter receptacles and causes a flow of oil dow-nwardlytrom the inner receptacle and upwardly into the space hetween the two receptacles and the compression of and storage of energv in the .en-

trapped air in the chamber 19, thereby increasing the volume of the expansion space abovethe surfaceof the oil in-the inner-receptacle and reducing the gaseous pressure therein and preventing shock to both receptacles. By the yielding suspensionpf the double .oil receptacle the device as-an entirety may yield and thereby additionally absorb the shock. Upon the eventual relief of the-generated gases over the top of the oil receptacle the oil will returntoits normal position by the expansion of-the compressed entrapped air or gases, which will forcibly return the oil and the switch will be in readiness to interrupt the circuit again.

I claim;

-1. An oil receptacle for electricswitches comprising a unitary structure having outer and inner walls peripherally spaced from strengthen the oil receptacle as an entirety.

each other arranged to form a closed top outer chamber and an open topinner chamber in communication below the oil level in the receptacle and means removably to secure the receptacle yieldingly to an electric switch.

2. An oil receptacle for electric switches comprising'a unitary structurehaving outer and inner walls peripherally spaced from each-other arranged to form a closedtop outer chamber and an open top inner chamber in communication below the oil level in the receptacle and a manually controlled valve arranged at the top of the outer chamber.

3. An oil receptacle for electric switches having inner and outer peripherally spaced walls, said inner wall extended above the outer wall, and the top portion of said outer wall reflexed and secured to said inner wall 10 In testimony whereof, I have signed my 15 name to this specification.

GEORGE A. BURNHAM. 

